Many times, you'll love it. We just did two weeks near Arenal Volcano last year. My parents lived there for 10+ years and my mother (76) is there for six weeks right now. We are all hikers and my parents have done many mountain hikes there through their 70s without problem. They aren't athletic fit, but regular fit walkers or hikers should have no problem. Obviously bring plenty of water, sunblock, hat, snacks etc. Start the hike very early in the morning, plan to be back by noon if possible. You can turn back if it seems too long. It is often cloudy near the volcano which is a blessing re: heat and sun.

Where are you doing the zip-lining? Which company? I'd recommend canyoning over just zip-lining. Essentially you repel down a cliff face then make your way through the canyon by waterfall jumping, swimming, zip-lining and repelling. We did it with our 11 and 8 year old last year and had a great time. We also did horseback riding which we enjoyed. Rafting on the river is fun, lot of howler monkeys.

Consider the boat cruise around Lake Arenal if you need a less active day, beautiful perspective on the volcano. Also there is world class wind surfing on Lake Arenal if that interests you. My kids really enjoyed visiting and wildlife rehabilitation sanctuary as well.

I don't know the beaches that well as we mostly stay inland. Enjoy your trip!

I am one of the few people who did not like Costa Rica; but I think it was all about the season. We went over spring break a few years ago, which they (euphemistically) call the "gold season". I would call it brown/dead. It was also high 90s and very very humid. Our hotel, the Four Seasons, was spectacular but isolated. Our trip to the volcano was a flop ( a bit o' smoke, not much else).

You will not be making any of these mistakes ... go when it is green, don't listen to them say any other time is ok! (I think it is green in Dec.?) Don't do a daytrip to the volcano, spend more time in the area so you have a better chance of it being active.

Mtn makes a good point about seasons.

Arenal volcano is no longer active so you won't see more than smoke now unfortunately.

I don't know hotels and beach areas well so I can't comment. I dislike the Central Valley intensely, but it sounds like you're not spending time there. Petty crime is also a serious issue, so be sure to take the normal precautions. Costa Rica is best for an active vacation imo.

Sochi, The zip-line is Arenal
Sky Adventure Park Canopy Zip Line. Who did you book the canyoning with?

Mtn, We are going in Dec and will be at the volcano for 3 nights. Hope it wakes up a bit!

We love Costa Rica and go yearly. It's our favorite place to go during the winter.

We have traveled North, South, East and West because I wanted to truly get a feeling for this beautiful country.

It's true that not all zip lines are equal. We did Sky Trek and it was top notch. Very high, very fast, very long and scary! It's near Arenal so maybe you can look into it.

I'm assuming the Nectandra is hanging bridges? Loved the hanging bridge hikes.

For me, the places that we stay are just as important as what we do. Basically, we now go to relax, so we like places that have monkeys and native animals on the property.

I agree with Mtn about the volcano. If you have been to Hawaii or other similar volcanic places, you will be disappointed. The year we went to Arenal, we took our daughters. We have a great picture of all of us with the volcano behind us. We paired this trip with hot water springs, so only stayed up there for half a day. The hikes can be tricky and steep, but if your parents are fit, they can manage it. It's a vertical country!

It will be humid and hot at the places that you will be going. But, if you ever go again, you can experience arid weather way north. There are cactus pants growing up there!

We were there several years ago. We flew into Liberia and stayed in the Guanacaste province, way up on the northwest side of the country. Here's what I remember: monkeys in the trees and huge iguanas wandering around the pool RIGHT IN OUR RESORT; a horseback tour into the forest, a tour of an aloe and pineapple plantation, and a trip up into the mountains to a pottery.